1. Field of the Invention
The present invention relates to a manufacturing method for a stacked device composed of a plurality of semiconductor chips stacked together, each semiconductor chip being formed with a device such as IC and LSI on the front side.
2. Description of the Related Art
In a semiconductor device fabrication process, a plurality of crossing streets (division lines) are formed on the front side of a substantially disk-shaped semiconductor wafer to partition a plurality of regions where devices such as ICs and LSIs are respectively formed. The semiconductor wafer having the devices in the partitioned regions is divided along the streets to manufacture a plurality of individual semiconductor chips. For the purposes of size reduction and higher functionality of equipment, a stacked device composed of a plurality of semiconductor chips stacked together has been put to practical use. This stacked device is manufactured by stacking a plurality of semiconductor wafers each formed with a plurality of devices on the front side to obtain a stacked wafer and next cutting this stacked wafer along the streets (see Japanese Patent Laid-open No. Sho 60-206058, for example).
If the thickness of each semiconductor wafer is reduced to 50 μm or less, for example, by grinding to further reduce the size of each stacked device, there is a problem such that each semiconductor wafer is easily broken, so that the lamination of the plural semiconductor wafers becomes difficult. Further, if the stacked wafer formed by stacking a plurality of semiconductor wafers each reduced in thickness is cut along each street by using a cutting blade, there is a problem such that the side surface of each stacked device may become chipped to cause a degradation in quality of each stacked device.